Essa superfície de fricção global enumera a velocidade de deslocamento terrestre para todos os pixels terrestres entre 85 graus norte e 60 graus sul para um ano nominal de 2019. Ela também inclui a velocidade de viagem "somente a pé", usando apenas meios de transporte não motorizados.
Este mapa foi produzido em colaboração entre o MAP (Universidade de Oxford), o Telethon Kids Institute (Perth, Austrália), o Google e a Universidade de Twente, na Holanda.
Este projeto se baseia em trabalhos anteriores publicados por Weiss et al 2018 (doi:10.1038/nature25181). Weiss et al. (2018) usaram conjuntos de dados de vias (compreendendo o primeiro uso em escala global do Open Street Map e dos conjuntos de dados de vias do Google), ferrovias, rios, lagos, oceanos, condições topográficas (inclinação e elevação), tipos de cobertura do solo e fronteiras nacionais. Cada um desses conjuntos de dados recebeu uma ou mais velocidades de deslocamento em termos de tempo para atravessar cada pixel desse tipo. Em seguida, os conjuntos de dados foram combinados para produzir uma "superfície de fricção", um mapa em que cada pixel recebe uma velocidade nominal geral de deslocamento com base nos tipos que ocorrem nele. Para o projeto atual, criamos uma superfície de atrito atualizada para incorporar melhorias recentes nos dados de vias do OSM.
As diferenças entre essa superfície de atrito e a versão de 2015 (Weiss et al., 2018) não indicam necessariamente mudanças na infraestrutura (por exemplo, construção de novas estradas). Essas discrepâncias têm muito mais chances de estar associadas à melhoria da qualidade dos dados, principalmente atualizações feitas na cobertura de vias do OSM. Por isso, as comparações entre as superfícies de fricção e os mapas de tempo de viagem resultantes precisam ser feitas com cuidado e geralmente não devem ser interpretadas como representando mudanças no acesso ao longo do tempo.
Esse mapa representa a velocidade de viagem desse processo de alocação, expressa em unidades de minutos necessários para viajar um metro. Ele forma o conjunto de dados subjacente por trás do mapa global de acessibilidade de assistência médica descrito no artigo referenciado.
Os créditos do conjunto de dados de origem são descritos no artigo acompanhante.
Bandas
Tamanho do pixel 927,67 metros
Bandas
Nome
Unidades
Mín.
Máx.
Tamanho do pixel
Descrição
friction
minutos/metro
0,000429
87,3075
metros
Velocidade de viagem terrestre.
friction_walking_only
minutos/metro
0.012
87,3075
metros
Velocidade de deslocamento terrestre usando transporte não motorizado.
D.J. Weiss, A. Nelson, C.A. Vargas-Ruiz, K. Gligorić, S. Bavadekar,
E. Gabrilovich, A. Bertozzi-Villa, J. Rozier, H.S. Gibson, T. Shekel,
C. Kamath, A. Lieber, K. Schulman, Y. Shao, V. Qarkaxhija, A.K. Nandi,
S.H. Keddie, S. Rumisha, E. Cameron, K.E. Battle, S. Bhatt, P.W. Gething.
Mapas globais do tempo de deslocamento até as instituições de saúde. Nature Medicine (2020).
Essa superfície de fricção global enumera a velocidade de deslocamento terrestre para todos os pixels terrestres entre 85 graus norte e 60 graus sul para um ano nominal de 2019. Ela também inclui a velocidade de viagem "somente a pé", usando apenas meios de transporte não motorizados. Este mapa foi produzido em colaboração entre a MAP (Universidade de Oxford), a Telethon …
[null,null,[],[[["\u003cp\u003eThis dataset provides a global friction surface, representing land-based travel speed for all land pixels between 85 degrees north and 60 degrees south for the year 2019.\u003c/p\u003e\n"],["\u003cp\u003eIt includes both overall travel speed and "walking-only" travel speed, using non-motorized means of transportation.\u003c/p\u003e\n"],["\u003cp\u003eThe friction surface was created by combining datasets for roads, railways, rivers, lakes, oceans, topographic conditions, landcover types, and national borders, assigning each a speed of travel.\u003c/p\u003e\n"],["\u003cp\u003eDeveloped through a collaboration between the Malaria Atlas Project (MAP), Telethon Kids Institute, Google, and the University of Twente.\u003c/p\u003e\n"],["\u003cp\u003eIt is important to note that differences between this friction surface and previous versions may be due to improved data quality rather than actual infrastructure changes.\u003c/p\u003e\n"]]],[],null,["# Global Friction Surface 2019\n\nDataset Availability\n: 2019-01-01T00:00:00Z--2020-01-01T00:00:00Z\n\nDataset Provider\n:\n\n\n [Malaria Atlas Project](https://malariaatlas.org/research-project/accessibility-to-cities/)\n\nTags\n:\n [accessibility](/earth-engine/datasets/tags/accessibility) [jrc](/earth-engine/datasets/tags/jrc) [map](/earth-engine/datasets/tags/map) [oxford](/earth-engine/datasets/tags/oxford) [population](/earth-engine/datasets/tags/population) [twente](/earth-engine/datasets/tags/twente) \nfriction \n\n#### Description\n\nThis global friction surface enumerates land-based travel speed for all land pixels between 85 degrees north and 60 degrees south for a nominal year 2019. It also includes \"walking-only\" travel speed, using non-motorized means of transportation only.\nThis map was produced through a collaboration between MAP (University of Oxford), Telethon Kids Institute (Perth, Australia), Google, and the University of Twente, Netherlands.\nThis project builds on previous work published by Weiss et al 2018 ([doi:10.1038/nature25181](https://doi.org/10.1038/nature25181)). Weiss et al (2018) utilised datasets for roads (comprising the first ever global-scale use of Open Street Map and Google roads datasets), railways, rivers, lakes, oceans, topographic conditions (slope and elevation), landcover types, and national borders. These datasets were each allocated a speed or speeds of travel in terms of time to cross each pixel of that type. The datasets were then combined to produce a \"friction surface\"; a map where every pixel is allocated a nominal overall speed of travel based on the types occurring within that pixel. For the current project, an updated friction surface was created to incorporate recent improvements within OSM roads data.\nDifferences between this friction surface and the 2015 version (Weiss et al. 2018) are not necessarily indicative of changes in infrastructure (e.g., new roads being built). Such discrepancies are far more likely to be associated with improved data quality, in particular updates made to OSM road coverage. As a result, comparisons between the friction surfaces and resulting travel time maps should be done cautiously and generally not interpreted as representing changes in access over time.\nThis map represents the travel speed from this allocation process, expressed in units of minutes required to travel one meter. It forms the underlying dataset behind the global healthcare accessibility map described in the referenced paper.\n\nSource dataset credits are as described in the accompanying paper.\n\n### Bands\n\n\n**Pixel Size**\n\n927.67 meters\n\n**Bands**\n\n| Name | Units | Min | Max | Pixel Size | Description |\n|-------------------------|---------------|----------|---------|------------|--------------------------------------------------------|\n| `friction` | minutes/meter | 0.000429 | 87.3075 | meters | Land-based travel speed. |\n| `friction_walking_only` | minutes/meter | 0.012 | 87.3075 | meters | Land-based travel speed using non-motorized transport. |\n\n### Terms of Use\n\n**Terms of Use**\n\nThis work is licensed under a [Creative Commons Attribution\n4.0 International License](https://creativecommons.org/licenses/by/4.0/).\n\n### Citations\n\nCitations:\n\n- D.J. Weiss, A. Nelson, C.A. Vargas-Ruiz, K. Gligorić, S. Bavadekar,\n E. Gabrilovich, A. Bertozzi-Villa, J. Rozier, H.S. Gibson, T. Shekel,\n C. Kamath, A. Lieber, K. Schulman, Y. Shao, V. Qarkaxhija, A.K. Nandi,\n S.H. Keddie, S. Rumisha, E. Cameron, K.E. Battle, S. Bhatt, P.W. Gething.\n Global maps of travel time to healthcare facilities. Nature Medicine (2020).\n\n### Explore with Earth Engine\n\n| **Important:** Earth Engine is a platform for petabyte-scale scientific analysis and visualization of geospatial datasets, both for public benefit and for business and government users. Earth Engine is free to use for research, education, and nonprofit use. To get started, please [register for Earth Engine access.](https://console.cloud.google.com/earth-engine)\n\n### Code Editor (JavaScript)\n\n```javascript\nvar dataset = ee.Image('Oxford/MAP/friction_surface_2019');\nvar landBasedTravelSpeed = dataset.select('friction');\nvar visParams = {\n min: 0.0022,\n max: 0.04,\n palette: [\n '313695', '4575b4', '74add1', 'abd9e9', 'e0f3f8', 'ffffbf', 'fee090',\n 'fdae61', 'f46d43', 'd73027', 'a50026'\n ],\n};\nMap.setCenter(43.55, 36.98, 4);\nMap.addLayer(landBasedTravelSpeed, visParams, 'Land-based travel speed');\n```\n[Open in Code Editor](https://code.earthengine.google.com/?scriptPath=Examples:Datasets/Oxford/Oxford_MAP_friction_surface_2019) \n[Global Friction Surface 2019](/earth-engine/datasets/catalog/Oxford_MAP_friction_surface_2019) \nThis global friction surface enumerates land-based travel speed for all land pixels between 85 degrees north and 60 degrees south for a nominal year 2019. It also includes \"walking-only\" travel speed, using non-motorized means of transportation only. This map was produced through a collaboration between MAP (University of Oxford), Telethon ... \nOxford/MAP/friction_surface_2019, accessibility,jrc,map,oxford,population,twente \n2019-01-01T00:00:00Z/2020-01-01T00:00:00Z \n-60 -180 85 180 \nGoogle Earth Engine \nhttps://developers.google.com/earth-engine/datasets\n\n- [](https://doi.org/https://malariaatlas.org/research-project/accessibility-to-cities/)\n- [](https://doi.org/https://developers.google.com/earth-engine/datasets/catalog/Oxford_MAP_friction_surface_2019)"]]
